The invention is an apparatus for cracking nuts, and more particularly an apparatus for shucking pecans that produces whole halves at a very high percentage.
The prior art of shucking nuts, and in particular shucking pecans using automated or partially automated cracking devices, reads on basically two types of nut crackers, wherein a type is distinguished in terms of how compressive forces are created and applied to the shell of the nut. In the first type, compressive forces are applied simultaneously to substantially the entire surface of the shell, and in the second type the compressive forces are applied progressively, and principally perpendicularly to the longitudinal walls of the shell. The first type of nut cracker usually creates the compressive forces through an collection of rods which in-cage the nut and crush the shell. The second type, which is better suited for automation in that this type usually requires fewer active elements, conveys the nut into a progressively narrower nip which therein causes the longitudinal walls of the shell to be crushed. Illustrative of the first type of nut cracker is Miller' U.S. Pat No. 3,965,810 patent. Miller's nut cracker is comprised of a plurality of rods mounted distally in a pair of handled circular plates having a center aperture. When the handles are twisted, the rods constrict radially, and therein apply leveraged compressive force to the shell of a nut positioned within the rods. An illustration of the second type of nut cracker is Joyama' U.S. Pat No. 4,819,331 invention. Joyama's automated nut cracker looks similar to a centrifugal pump, wherein the gears act to crush a pair of opposing longitudinal walls of the shell, while pumping the nut through the progressively narrower constriction.
Some of the prior art has elements of both types of nut crackers. Daugherty's pecan shucker' U.S. Pat No. 5,544,574, forces the nut through a multitude of rollers using an axial longitudinal rod, wherein the rollers apply circumferential compressive forces to the entering end portion of the shell of the nut. The forces are similar to the first type of cracker, in that they are circumferential, however, similar to the second type in that the compressive forces are acting on only a portion of the nut. In Packwood's nut cracking machine' U.S. Pat No. 4,073,032, the rollers are driven, and there is no need for a rod, however the nut will assume the same orientation, such that an end portion of the nut will be compressed circumverentially. Unanimous to all the prior art is that the nut is always under compression while in the nut cracker, therein not enabling a time for the nut to reorientate. These two factors, constant compression and no reorientation limit the mechanisms by which the shell can separate from the kernel.
The success of the shucking process is generally gauged on the efficiency with which the shell is relieved from the nut without damaging the kernel, and in the case with pecans, the percentage of whole halves has traditionally been the benchmark.
It has been observed that while the first type of nut cracker produces a relatively good percentage of whole halves, the yield is not as high as anticipated. A possible explanation for the lowered efficiency is that while the compressive forces are uniform, their combined effect produces a more rigid shell, because the elongated round shell is under tension inward, and the higher rigidity results in a more explosive type cracking action.
The second type of nut cracker applies force principally to just the sides of the shell, consequently the kernel frequently breaks apart leaving portions of the kernel in the parabolic ends of the pecan, as the nut is never reorientated in the nip, and compression is therefore never applied to the ends of the nut. This second type of nut cracker can have very high through-puts, but often lower efficiency in terms of percentage of whole pecan halves
An improved apparatus for cracking nuts, and particularly pecans, would have a mechanical action that would sequentially apply just enough compressive force to a section of the shell so as to crack the shell without damaging the kernel, and continue to repeat the mechanical action until a sufficient number of sections of the shell had been cracked so as to liberate the kernel from the shell, and in so doing produce a very high percentage of whole halves. It necessarily follows that said mechanical action would require either the reorientation of the nut after cracking a section, or reorientation of the spatial axis of the compressive force, relative to the nut